I am pretty sure I was doing a full reboot. I guess the problem come from the point where I have close by force the system when the GUI got stuck.
I should have restart only the gdm.
With this occasion I have upgrade to last version of ubuntu.
To backup my data I have stop gdm and use startx to have access to some of gnome applications. So now I no longer have this problem.
Last edited by qt-x; 11-06-2010 at 10:21 AM.